We propose to investigate psychosocial variables related to risk for AIDS in a cohort of 1200 single men in San Francisco. We have the unique opportunity to complete these studies by collaborating with a NIAID funded project entitled "A Prospective Sero-Epidemiological Study of Acquired Immune Deficiency Syndrome (AIDS) in Homosexual Men Residing in San Francisco." Under funding from that project: (1) a probability sample of disease free single males (1000 homosexual and 200 heterosexual) 25-54 years of age will be recruited; (2) it is estimated that between 45 and 75 cases of AIDS will develop during 3 years of follow-up; (3) each study subject will receive a physical examination and donate specimens for serological, virological, and chemical study. With the limited additional funding we are requesting in this proposal, we will be able to document: (1) pyschosocial and behavioral risk factors for AIDS; (2) the attitudes, behaviors, and beliefs of the cohort over time; (3) study psychosocial consequences of diagnoses of AIDS or of symptoms possibly associated with later development of AIDS; and (4) explore psychoneuroimmunological relationships. Psychosocial variables to be investigated will include social support and stress. Other behavioral variables to be collected include sexual activity (frequency, type, and location), drug and alcohol use, and family and personal history of disease. The creation of this data set will permit us to study the specific questions stated and also allow for the creation of repository of invaluable information available for study later as more hypotheses suggest themselves.